The issue with this theory is it completely ignores that women can be gay too. The hypothesis put forward here only takes account of gay men and says women infected by the parasite also become attracted to men.
Another issue I have is that the rodents may have changed their sexual preference, but they didn't become homosexuals. In fact their sexual preference moved away from their own species. To then jump from "rats changed so humans therefore turn gay" is just that, a jump.
And then let's just look at what is put forward here vs the facts - I am not aware of ANY study that shows that T. Gondlii or toxoplasm 5 makes you gay. Instead it actually has the opposite effect. Studies show it changes testosterone levels, jacking them up in men and lowering them in women. So rather than getting a faggot you're more likely to get a meathead from the infection. It also impairs motor skills.
You can tell this is pseudo science very clearly at one point - "Toxoplasms are found in 9% of newborns (Hrmm where have we seen this figure before, oh right it's the same percentage of homosexuals in the US". That's not how science works. 9% of the US population thinks being in the KKK is ok, does that mean Toxoplasms and T. Gondlii are responsible? You can't just line statistics up like that and call it science, especially if you aren't willing to accept that other 9% will fit in that same box. By the logic given here I could say "Every white supremacist is also a faggot, because 9%".
TLDR - this is psuedoscience bullshit that reinforces an idea you already have, therefore you want it to be true and accept it as truth.